Indwelling device

ABSTRACT

A medical device for insertion into a body having a surface covered by a detachable cover. The cover may be detached from the surface and removed from the body while the device is inserted in the body. The device may be, for example, a catheter, cannula, drain, stent, pacemaker, or electrode.

FIELD OF THE INVENTION

The present invention is in the field of medical devices, and morespecifically relates to indwelling medical devices.

BACKGROUND OF THE INVENTION

There are many medical devices that are inserted into the body and leftindwelling for a prolonged period of time. These include, for example,various types of catheters, cannulae, drains, implants, stents,pacemakers, electrodes and other devices. Some of these devices, such asa urinary catheter, when in use, extend from the exterior of the bodyinto the body interior, passing through an orifice on the body surface.The orifice may be a natural orifice (e.g. mouth, meatus, nostrils,etc.) or an artificial orifice (e.g. a hole formed in the skin by asurgical incision). Other indwelling devices, such as a pacemaker orstent, are completely enclosed inside the body during use. Accessingthese devices typically requires surgical incising or other invasiveapproaches.

Although using indwelling devices is a common medical procedure, it isoften limited due to formation of biofilm such as calcifications andother debris, and colonization of microorganisms, such as bacteria andfungi, on the surface of the device. This may cause inflammation andfurther infection around the device. The formation of biofilm andcontamination is common with exposed indwelling devices, limiting theamount of time that they may be left in the body before having to beremoved and possibly replaced with a new device.

Contamination of the device and tissues surrounding it may occur as thedevice is inserted into the body. For example, the end of a urethraclosest to the meatus is naturally contaminated with various infectiousagents, while the remainder of the urethra, nearer to the urinarybladder is normally sterile. During insertion of a catheter through theurethra to the urinary bladder, the catheter contacts infectious agentsin the beginning of the urethra and spreads them up the urethra into thenormally sterile portion and into the bladder. In order to reduce thespread of microorganisms up the urethra during insertion of a urinarycatheter, it is known to first insert a hollow sheath into the beginningof the urethra that extends in the urethra to just beyond thecontaminated region. A urinary catheter is then inserted through thesheath into the normally sterile part of the urethra, and into thebladder. The sheath thus intervenes between the catheter and themicroorganisms in the infected part of the urethra, and thus decreasesthe chance of microorganisms spreading into the normally sterile portionof the urethra and into the bladder. After insertion of the catheter,the sheath is withdrawn from the body. Such sheaths are disclosed, forexample, in U.S. Pat. No. 5,417,666.

Microorganisms may also migrate along an exposed indwelling device afterits insertion along the outside surface of the device at its interfacewith the surrounding tissue. In order to inhibit the migration ofmicroorganisms along the device, it is known to impregnate the devicewith antiseptic substances that are released from the catheter overtime. A catheter designed to release antiseptic substances is disclosed,for example, in U.S. Pat. No. 3,598,127. Antiseptic impregnation,however, is not effective in the prevention of biofilm formation and isof very limited value in preventing infection due to the development ofresistance among the microorganisms to the antibiotic.

SUMMARY OF THE INVENTION

It has now been found that it is possible to prevent the build-up ofbiofilm on the surfaces of indwelling medical devices by means ofproviding removable covers. By means of this arrangement, biofilmcomponents become deposited on the surface of a cover instead of on thesurface of the medical device itself. This cover may then be removedwithout disturbing the positioning or functioning of the indwellingdevice to which said cover was attached, thereby removing the built-upbiofilm from the region of the device, and from the body. The act ofremoving the cover exposes either a further cover, enabling the removalprocess to be repeated, or, the external surface of the indwellingdevice itself. Unexpectedly, the inventors have found that it ispossible to construct a covered device, such that the desiredfunctioning thereof (for example the passage of fluids through acatheter or the mechanical dilatory action of a stent) is not affectedor influenced by the presence of one or more covers on the surface ofthe device.

The term “biofilm”, explained hereinabove, refers to the build-up ofbiologically-derived matter such as calcified material and other debris,as well as microorganisms, such as bacteria and fungi, on the surface ofthe device. This may cause inflammation and further infection around thedevice. In certain locations and in certain circumstances the biofilmand associated inflammatory processes may lead to undesirable blood clotformation.

The present invention is thus primarily directed to indwelling medicaldevices having an outer surface, at least a portion of which isprotected by a manually detachable cover. During insertion, the cover isattached to the surface so as to prevent relative movement of thesurface and the cover. This allows the integrity of the device and coverto be maintained during insertion. Once the covered device (e.g.catheter, stent, drain etc.) has been inserted into the desiredoperating location, said device may be manipulated or operated in thenormal manner, without any hindrance or loss of functionality arisingfrom the presence of the cover. At any time after insertion, the covermay be detached from the shaft and removed from the body, leaving thedevice in place. Removing the cover from the device removes the biofilmand contamination that has accumulated on the cover.

The cover is preferably made from non-allergic biocompatible materialssuch as natural rubber, silicone rubber, latex, woven metal mesh,parylene, polyvinylchloride, polyurethane, mylar, nylon and the like.The cover may be impermeable to body fluids or microorganisms. The covermay have a rough or smooth surface.

The covered device provided by the present invention may comprise any ofthe different types of indwelling medical devices known in the art. Inparticularly preferred embodiments, however, the medical device isselected from the group consisting of:

-   -   (a) a catheter (e.g. a urinary catheter, venous catheter,        arterial catheter dialysis catheter);    -   (b) a cannula;    -   (c) a drain;    -   (d) a stent;    -   (e) a pacemaker; and    -   (f) an electrode.

In a preferred embodiment, the device has an outer surface that isprotected by a stack of two or more sequentially detachable covers. Afirst, innermost, cover is in direct contact with the outer surface ofthe device. A second detachable cover is in contact with the firstcover, so that the first cover is between the second cover and thesurface. Additional covers may also be present, as required. At any timeafter insertion of the device into the body, the outermost cover may bedetached from the surface and removed from the body, leaving the devicein place with one less cover over the surface. The newly exposedoutermost cover may, later on, be detached from the surface and removedfrom the body. This process may be repeated until all of the covers havebeen removed. When using multiple covers, the covers may be made fromthe same material as the surface of the device or from a differentmaterial. The covers may be identical or different. They may be madefrom different materials or the same material. The thickness of eachlayer may be the same or different.

A detachable cover for a device may be made using a pre-formed coverthat is applied to the surface. A cover may be formed having a lumenthat is dimensioned to receive the entire device, or a portion of it inthe lumen. Alternatively, a liquid coating substance may be applied tothe device or to a portion of its surface and allowed to solidify bycuring, polymerizing, or drying. For example, a 2:1 solution of siliconerubber:toluene may be applied to the surface and allowed to dry andcure. The coating substance may be applied to the device or an outermostdetachable cover previously applied to the surface, for example, bybrushing, immersion, spraying, or any other method of deposition.

Two adjacent members (a detachable outermost cover and the surface ofthe device, or two adjacent detachable covers on a multiple coateddevice), may be reversibly attached to each other by any known method.For example, an adhesive may be introduced between the members andallowed to cure. The bond formed by the adhesive is subsequently brokenwhen desired, for example, by applying an axial or radially outwardforce to the outermost member so as to break the bond. Alternatively,the bond may be broken by introducing a fluid between the members thatbreaks the bond either chemically or mechanically. As yet anotheralternative, the bond may be broken over time, either spontaneously orduring prolonged contact of the adhesive with body fluids such as bloodplasma or urine.

The reversible attachment of the two adjacent members may extend alongthe entire contact area between the members, or only at specific regionsbetween the members. For example, one or more clips may be disposed onthe device that presses the outermost cover to the underlying member atvarious locations. The clips may be formed, for example, by a rubberring that may be rolled onto the outermost layer. The outermost layer isdetached by cutting the ring or by rolling it off the outermost layer.The clip may be a toroidal balloon that constricts the members wheninflated and releases the attachment when deflated.

A detachable cover may be made from an elastic material. An elasticcylinder may be stretched over the shaft of a catheter or overdetachable covers already present on the shaft and allowed to contractwith the shaft and any previously existing detachable covers in itslumen. In this case, a reversible attachment is formed between the newcover and an adjacent member by the elastic forces of the new outermostcover. The attachment may be broken by making a longitudinal cut alongthe outermost cover. The cover may have one or more lines of preformedperforations that are easily torn by splaying apart an end of thecoating.

The mechanical removal of the detachable cover(s) may also be achievedby means of the use of a fixed, proximally-located knife blade. Thisblade is shaped and disposed such that the proximal end of the outermostcover may be pulled towards the blade, and subsequently splitlongitudinally by the action of the stationary blade on theproximally-drawn cover. In this manner, the apposition and attachment ofthe outermost cover to the adjacent cover or external surface of theindwelling device is disrupted, thus allowing the removal of saidoutermost cover from said device and from the body.

The space between the device and a cover or between two adjacent coversmay contain material to reinforce the attachment or to enhance relativesliding. The material may repel deposits, and/or containpharmaceutically-active agents, including but not limited toanti-microbial agents such as antibiotics. The interface material can bethe same or different, for each pair of adjacent members. For example,mineral oil may be present to enhance sliding and prevent penetration ofcontamination between the members.

In a particularly preferred embodiment of the device of the presentinvention, sealing elements are present at the distal and/or proximalextremities of the covered device. The presence of these sealingelements prevents the ingress of liquids such as blood, urine, tissuefluid and so on into the space between pairs of adjacently-disposedcovers or into the space between the innermost cover and the externalsurface of the medical device itself. In another aspect, the presentinvention is also directed to indwelling medical devices having an inneror luminal surface, at least a portion of which is protected by eitherone manually detachable cover or a stack of two more sequentiallydetachable covers. This particular embodiment of the device of theinvention is particularly suitable for use in applications where it isdesirable to prevent the formation and growth of blood clots on theluminal surface of indwelling devices such as venous and arterialcatheters. During insertion, the cover is attached to the surface so asto prevent relative movement of the surface and the cover. This allowsthe integrity of the device and cover to be maintained during insertion.Once the covered internal device (e.g. internal surface of a catheter ordrain) has been inserted into the desired operating location, saiddevice may be manipulated or operated in the normal manner, without anyhindrance or loss of functionality arising from the presence of thecover. At any time after insertion, the cover may be detached from theshaft and removed from the body, leaving the device in place. Removingthe cover from the device removes any blood clots, contamination andother biofilm deposits that may have accumulated on the cover. All ofthe various different embodiments and technical features described abovein relation to the devices having external covers also apply to thedevices having internal covers as described immediately hereinabove.

In a further aspect, the present invention also provides a method forpreventing biofilm buildup on the surface of an indwelling medicaldevice that has been inserted into the body of a subject, said methodcomprising the steps of:

-   -   a) providing a medical device fitted with a detachable cover        attached to at least a portion of its outer surface, such that        the presence of said cover does not interfere with the intended        function of said device;    -   b) inserting said device together with its attached cover into        the body of the subject;    -   c) detaching the cover from the outer surface of the medical        device and removing said cover from the body together with any        biofilm deposited on the surface of said cover, while leaving        the device inside the body such that it may continue to fulfill        its intended function.

The present invention also provides a further method for preventingbiofilm buildup on the surface of an indwelling medical device that hasbeen inserted into the body of a subject, said method comprising thesteps of:

-   -   a) providing a medical device fitted with a stack of two or more        sequentially detachable covers, such that the innermost cover is        attached to at least a portion of its outer surface, and wherein        the presence of said stack of covers does not interfere with the        intended function of said device;    -   b) inserting said device together with its attached cover into        the body of the subject;    -   c) detaching the outermost cover from the stack of sequentially        detachable covers and removing said cover from the body together        with any biofilm deposited on the outer surface thereof, while        leaving the device inside the body such that it may continue to        fulfill its intended function;    -   d) subsequently repeating step (c) for the one or more remaining        outermost covers.

In a preferred embodiment of the above-disclosed methods for preventingbiofilm buildup on the surface of an indwelling medical device, saiddevice is selected from the group consisting of:

-   -   (a) a catheter;    -   (b) a cannula;    -   (c) a drain;    -   (d) a stent;    -   (e) a pacemaker; and    -   (f) an electrode.

In one particularly preferred embodiment of the method of the presentinvention, the device is a urinary catheter. In another particularlypreferred embodiment, the device is a venous catheter. In a furtherparticularly preferred embodiment, the device is a dialysis catheter.

All the above and other characteristics and advantages of the presentinvention will be further understood from the following illustrative andnon-limitative examples of preferred embodiments thereof.

BRIEF DESCRIPTION OF THE DRAWINGS

In order to understand the invention and to see how it may be carriedout in practice, preferred embodiments will now be described, by way ofnon-limiting examples only, with reference to the accompanying drawings,in which:

FIGS. 1 a-1 d show an indwelling device having a tearable cover inaccordance with one embodiment of the invention;

FIGS. 2 a-2 c show an indwelling device having a cutable cover inaccordance with another embodiment of the invention;

FIGS. 3 a-3 d show an indwelling device having a rollable cover inaccordance with another embodiment of the invention;

FIGS. 4 a-4 c show an indwelling device having a helical cover inaccordance with another embodiment of the invention;

FIGS. 5 a-5 e show an indwelling device having a cover attached withinternal balloons in accordance with another embodiment of theinvention;

FIG. 6 shows use of a clamp securing the distal end of a cover to asurface;

FIGS. 7 a and 7 b show an indwelling device having a cover attached onan inner surface;

FIGS. 8 a-8 d show an indwelling device having a tearable cover inaccordance with another embodiment of the invention;

FIGS. 9 a-9 c show a system for preparing a cover on a mandrel inaccordance with one embodiment of the invention; and

FIGS. 10 a-10 h show a system for transferring a cover from a mandrelonto a device.

FIGS. 11 a-11 d show an indwelling device having a cover attached to itsouter surface, said cover being fitted with proximal and distal sealingelements and a fixed cutting blade.

DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION

The invention will now be described by non-limiting embodiments. For thesake of clarity, the invention is exemplified by devices having aslender shaft such as catheters, cannulae, and drains. This is by way ofexample only, however, and the invention is not limited to such devices.Other devices having detachable covers are included within the scope ofthe invention, such as implants, stents, and pacemakers.

First Embodiment

FIG. 1 a shows an indwelling device 100 in accordance with a firstembodiment of the invention. The device 100 has a proximal end 102, adistal end 104, and a cylindrical shaft 105 that may be solid or hollow.The shaft 105 is contained in an outer cover 110 having the generalshape of a thin cylindrical shell. The outer cover 110 is formed from abiocompatible, elastic material, such as latex, that was stretched overthe shaft 105, and allowed to contract on the shaft 105. The outer cover110 is reversibly attached to the shaft 105 by circumferential elasticforces in the outer cover 110 that are exerted on the shaft 105. Thisprevents slipping of the outer cover 110 over the shaft 105 duringinsertion of the device 100 into the body, and maintains the outer cover110 on the shaft 105 after insertion.

The outer cover 110 is formed from two materials. The first material isused to form the cover except in a narrow strip 125 that is formed froma second material. The two materials are joined at two parallel seams120 a and 120 b extending along the length of the outer cover 110. Thestrip of 125 formed from the second material preferably extendscircumferentially for less than one quarter of the circumference of theouter cover 110. The first material has a relatively high tear stress,for example, a silicone rubber having a tear stress of 25 to 50 kN/M.The second material is a material having a relatively low tear stress,such as a silicone rubber with a tear stress of less than 5 kN/M. Thepreparation of silicone rubbers and other materials having a particulartear stress are known in the art.

Between the shaft 105 and the outer cover 110 is a cord 130. The cord isattached at one of its ends to the distal end of the strip 125. At itsother end, the cord extends beyond the proximal end of the coating. Aring 150 holds the end of cord 130 on the shaft 105. As shown in FIG. 6,the device 100 may optionally comprise a distally located annular clamp610 that secures the distal end of the outer cover 110 to the shaft 105and prevents debris from accumulating under the distal end of the outercover 110 during insertion.

FIG. 1 b shows the catheter of FIG. 1 a after insertion into the body.The catheter 100 was inserted into the body through a hole 135 on thebody surface 140. The hole 135 may be a natural hole on the body surface(e.g. mouth, meatus, nostrils, etc.) or an artificial hole (e.g. a holeformed in the skin by a surgical incision). After insertion, theproximal end of the cord 130 extends through the hole 135 and is exposedon the body surface. This is by way of example only, and the device mayin use be completely enclosed within the body. In this case, a surgicalcut is made in order to access the proximal end of the cord 130.Relative movement of the shaft 105 and the outer cover 110 is preventedduring insertion due to the circumferential elastic forces of the outercover 110 on the shaft 105.

At any time after insertion, the outer cover 110 may be detached fromthe device 100 by removing the ring 150 and pulling the distal end ofthe cord 130. Pulling the cord 130 away from the body draws the distalend of the strip 125 into the space between the coating 110 and theshaft 105, tearing the distal ends of the seams 120 a and 120 b. (FIG. 1c). As the cord 130 continues to be pulled, tearing of the seams 120 aand 120 b progresses from the distal end towards the proximal end, untilthe entire strip 125 has been detached from the rest of the layer 110and removed from the body (FIG. 1 d). This detaches the outer cover 110from the shaft 105. The proximal end of the torn outer cover 110 may nowbe grasped and manually removed from the body leaving the device 100 inplace. If after removal of the outer cover 110, a new detachable outercover (not shown) becomes exposed on the shaft, the newly exposeddetachable layer may later on be removed from the device.

FIG. 9 shows a system, generally indicated by 900, for preparing thecover 110. A reservoir 905 contains a first liquid suspension 910 forpreparing the first material in the cover 110. A cylindrical mandrel 915is used upon which the cover 110 is to be formed. The mandrel 915 has adiameter corresponding to the inner diameter of the cover 110. A lengthof the mandrel 915 is submerged in the suspension 910. As the mandrel915 is withdrawn from the suspension 910, a layer 920 of the firstmaterial coating the mandrel is formed.

A wiper blade 925 is used to remove a portion of the coating 920 as themandrel 915 is withdrawn from the suspension 910. Above the wiper 925, anarrow strip 930 of the surface of the mandrel 915 thus becomes exposed.

A second reservoir 935 contains a second suspension 940 that is used toform the second material of the coating 110. The second suspension 940is delivered to the surface of the mandrel 915 through a tube 945. Anozzle 950 applies the second suspension to the exposed strip 930 of themandrel 915 surface, as the mandrel 915 is withdrawn from the firstsuspension 910. The second suspension 940 thus forms a coating 955 onthe mandrel 915 in the exposed strip 930 created by the wiper 925.

FIG. 9 c shows the mandrel 915 after having been removed from thereservoir 905. A cylindrical coating 960 has been formed on the mandrel915. The coating consists of the first portion 920 formed by the firstsuspension 910 and the second portion 955 formed by the secondsuspension 940. The mandrel 915 is then placed in an oven in order toallow the coating to cure so as to form the cover 110. The firstsuspension 910 thus formed the first material of the cover, and thesecond suspension 940 formed the second material.

FIG. 10 shows a system, generally indicated by 1000, for transferringthe cover 110 from the mandrel 915 to the shaft 105 of the device 100.The system 1000 is shown in plan view in FIG. 10 a and in cross-sectionin FIG. 10 b. The system 1000 has a housing 1005. A cylindrical tube1010 passes through the housing 1005 and has a diameter configured toalternately receive the coated mandrel 915 and the shaft 105 of thedevice 100, as described below.

FIG. 10 b shows the interior 1015 of the system 1000. A cylindricalspace 1020 surrounds the cylinder 1010. The wall 1022 that is common tothe space 1020 and the cylinder 1010 contains a plurality of pores 1025allowing the flow of air between the interior 1015 of the cylinder 1010and the space 1020. When the ends of the cylinder 1010 are sealed, asdescribed below, the chambers 1015 and 1020 may be evacuated by removingair in the chambers through a tube 1027 that is connected to a source ofnegative pressure (not shown).

FIG. 10 c shows the system 1000 after the mandrel 915 has been insertedinto the cylindrical tube 1010. As described above, the mandrel 915 iscontained in the cover 110 that is to be transferred from the mandrel915 to the shaft 105 of the device 100.

As shown in FIG. 10 d, the ends 128 of the cover 110 are then rolled offthe mandrel 915 and onto the ends of the tube 1010, thus sealing theends of the cylinder 1010. The chamber 1020 is then evacuated causingthe cover 110 to dissociate from the mandrel 915 and associate with theinner surface of the cylinder 1010, as shown in FIG. 10 e. Dissociationof the cover 110 from the mandrel 915 may be enhanced if the mandrel isformed with a hollow core 1030 that is confluent with the exterior bypores 1035 in the wall of the mandrel 915, as shown in FIG. 10 f. Asource of positive pressure (not shown) is applied to the core 1030 bymeans of a tube 1040. The mandrel is then removed from the cylinder 1010leaving the cover 110 mounted on the inner surface of the cylinder 1010,as shown in FIG. 10 f.

Now the shaft 105 of the device 100 is inserted into the cylinder 1010as shown in FIG. 10 g. The source of negative pressure is thendisconnected from the tube 1027, causing the cover 110 to dissociatefrom the wall of the cylinder 1010 and associate with the shaft 105 ofthe device 100, as shown in FIG. 10 h. The ends of the cover 110 arethen unrolled from the cylinder 1010 onto the shaft 105, and the shaft105 is removed from the interior of the cylinder 1010 with the cover 110in place.

Second Embodiment

FIG. 2 a shows an indwelling device 200 in accordance with anotherembodiment of the invention. The device 200 has a proximal end 202, adistal end 204, and a cylindrical shaft 205 that may be solid or hollow.The shaft 205 is contained in an outer cover 210 having the generalshape of a thin cylindrical shell. The outer cover 210 is formed from abiocompatible, elastic material, such as latex, that was stretched overthe shaft 205, and allowed to contract on the shaft 205. The outer cover210 is reversibly attached to the shaft 205 by circumferential elasticforces in the outer cover 210 that are exerted on the shaft 205. Thisprevents slipping of the outer cover 210 over the shaft 205 duringinsertion of the device 200 into the body, and maintains the outer cover210 on the shaft 205 after insertion.

As shown in the insert FIG. 2 a-I of FIG. 2 a, the shaft has alongitudinal groove 215 that forms a track for a blade 220. The blade220 is slidable along the groove 215. During insertion into the body,the blade 220 is positioned at the distal end of the groove 215. Betweenthe shaft 205 and the outer cover 210 is a cord 230. The cord isattached at one of its ends to the blade 220. At its other end, the cord215 extends beyond the proximal end of the coating.

FIG. 2 b shows the device 200 after insertion into the body. The device200 was inserted into the body through a hole 235 on the body surface240. The hole 235 may be a natural hole on the body surface (e.g. mouth,meatus, nostrils, etc.) or an artificial hole (e.g. a hole formed in theskin by a surgical incision). After insertion, the proximal end of thecord 230 extends through the hole 235 and is exposed on the bodysurface. This is by way of example only, and the device may in use becompletely enclosed within the body. In this case, a surgical cut ismade in order to access the proximal end of the cord 230. Relativemovement of the shaft 205 and the outer cover 210 is prevented duringinsertion due to the circumferential elastic forces of the outer cover210 on the shaft 205.

At any time after insertion, the outer cover 210 may be detached fromthe device 200 by pulling the proximal end of the cord 230. Pulling thecord 230 away from the body draws the blade 220 towards the proximal endof the shaft 205 thus making a longitudinal cut 233 in the cover 210.(FIG. 2 c). A guard 222 (FIG. 2 a-I) on the blade prevents the bladefrom cutting any underlying covers. As the cord 230 continues to bepulled, cutting of the cover 210 progresses from the distal end towardsthe proximal end, until the cut extends along the entire length of thecover 210. This detaches the outer cover 210 from the shaft 205. Theproximal end of the cut outer cover 210 may now be grasped and manuallyremoved from the body leaving the device 200 in place. If after removalof the outer cover 210, a new detachable outer cover (not shown) becomesexposed on the shaft, the newly exposed detachable layer may later on beremoved from the device.

Third Embodiment

FIG. 3 a shows a device 300 in accordance with another embodiment of theinvention. The device 300 has a proximal end 302, a distal end 304, anda cylindrical shaft 305. The shaft 305 is contained in an outer cover310 having the general shape of a thin cylindrical shell. The outercover 310 is formed from a biocompatible, elastic material, such aslatex. The outer cover 310 was formed from an inner cylindrical shell322 and an outer cylindrical shell 324. The inner and outer shells 322and 324 are welded together at a first circular seam 326 at its distalend and a second circular seam 327 at its proximal end. The outer cover310 was stretched over the shaft 305, and allowed to constrict on theshaft 305. The outer cover 310 is reversibly attached to the shaft 305by circumferential elastic forces in the outer cover 310 that areexerted on the shaft 305. This prevents movement of the outer cover 310relative to the shaft 305 during insertion of the device 300 andmaintains the outer cover 310 on the shaft 305 after insertion.

FIG. 3 b shows the device of FIG. 3 a after insertion into the body. Thecatheter 300 was inserted into the body through a hole 335 on the bodysurface 340. The hole 335 may be a natural hole on the body surface(e.g. mouth, meatus, nostrils, etc.) or an artificial hole (e.g. a holeformed in the skin by a surgical incision). The proximal end of theouter cover 310 extends through the hole 335 and is exposed on the bodysurface. This is by way of example only, and the device may in use becompletely enclosed within the body. In this case, a surgical cut ismade in order to access the proximal end of the outer cover 310.Relative movement of the shaft 305 and the outer cover 310 is preventedduring insertion due to the circumferential elastic forces of the outercover 310 on the shaft 305.

At any time after insertion, the outer cover 310 may be detached fromthe device 300 by causing the outer cylindrical shell 324 to slideproximally over the inner cylindrical shell 322. As shown in FIG. 3 c,this may be accomplished by placing a thumb 330 and an index finger 332on the outer cylindrical shell 324 and urging the outer cylindricalshell 324 to slide proximally over the inner cylindrical shell 322, asindicated by the arrow 342 This draws the distal end of the innercylindrical shell 322 into the outer shell 324, while the remainder ofthe inner shell remains stationary, relative to the shaft 305. As theouter shell 324 continues to slide proximally, the shaft 305 becomesprogressively more exposed at its distal end, as shown in FIG. 3 d. Thisprocess continues until the shaft 305 has been completely exposed andthe outer cover 310 has been removed from the body. If after removal ofthe outer cover 310, a new detachable outer cover (not shown) becomesexposed on the shaft, the newly exposed detachable layer may later on beremoved from the device.

Fourth Embodiment

FIG. 4 a shows an indwelling device 400 in accordance with anotherembodiment of the invention. The device 400 has a proximal end 402, adistal end 404, and a cylindrical shaft 405 that may be solid or hollow.The shaft 405 is contained in an outer cover 410 having the generalshape of a thin cylindrical shell. The outer cover 410 is formed from astrip of biocompatible material, such as latex or silicone rubber. Theouter cover 410 is formed by winding the strip of biocompatible materialin a helical pattern around the length of the shaft 405. Consecutiveturns of the helix overlap so as to completely cover the shaft 405. Thedistal end 411 of the strip is tucked under the first few turns of thehelix, so as to immobilize the distal end of the strip as shown in theinsert to FIG. 4 a. The proximal end of the strip is held in place by aring 425. The ring 425 has a lumen dimensioned to fit snugly on theshaft 405 and the proximal end of the outer cover 410. This preventsslipping of the outer cover 410 over the shaft 405 during insertion ofthe device 400 into the body, and maintains the outer cover 410 on theshaft 405 after insertion.

FIG. 4 b shows the device of FIG. 4 a after insertion into the body. Thedevice 400 was inserted into the body through a hole 435 on the bodysurface 440. The hole 435 may be a natural hole on the body surface(e.g. mouth, meatus, nostrils, etc.) or an artificial hole (e.g. a holeformed in the skin by a surgical incision). After insertion, theproximal end of the device 400, including the ring 425, extends throughthe hole 435 and is exposed on the body surface. This is by way ofexample only, and the device may in use be completely enclosed withinthe body. In this case, a surgical cut is made in order to access theproximal end of the device 400 and the ring 425. Relative movement ofthe shaft 405 and the outer cover 410 is prevented during insertion dueto the radial force of the ring 425 on the proximal end of the outercover 410, and the radial force of the last few turns of the helix onthe distal end of the outer cover 410.

At any time after insertion, the outer cover 410 may be detached fromthe device 400. Referring to FIG. 4 c, the ring 425 is removed from theshaft 405 and the outer cover 410 is unwound from its proximal end 408.(FIG. 4 c). The outer cover 410 continues to be unwound, until thedistal end of the outer cover 410 is freed. The proximal end of theouter cover 410 may now be grasped and manually removed from the bodyleaving the device 400 in place. If after removal of the outer cover410, a new detachable outer cover (not shown) becomes exposed on theshaft, the newly exposed detachable layer may later on be removed fromthe device.

Fifth Embodiment

FIG. 5 a shows an indwelling device 500 in accordance with anotherembodiment of the invention. The device 500 has a proximal end 502, adistal end 504, and a cylindrical shaft 505 that may be solid or hollow.The shaft 505 is contained in an outer cover 510 having the generalshape of a thin cylindrical shell.

The outer cover 510 is formed from a biocompatible, rigid material, suchas plastic or metal. One or more balloons 515 are located in a space 520formed between the outer cover 510 and the shaft 505. In FIG. 5 a, theballoons are shown in their deflated state. As shown in FIG. 5 b, beforeinserting the device 500 into the body, the balloons 515 are inflatedwith a fluid such as air or water. A syringe 525 containing the fluid530 is inserted into a valve 570.

The balloons are inflated by opening the valve 570 and depressing theplunger 550 of the syringe. The fluid 530 is conducted from the syringe525 through a first tube 560 and then through a second tube 565 runningalong the shaft 505 and then into each of the balloons 515. Wheninflated, the balloons apply a pressure to both the shaft 515 and theouter cover 510. The valve 540 is then closed to prevent fluid fromleaving the balloons. The outer cover 510 thus becomes reversiblyattached to the shaft 505 by the balloons 515 that are lodged betweenthe outer cover 510 and the shaft 505.

FIG. 5 c shows the device of FIGS. 5 and b after insertion into thebody. The device 500 was inserted into the body through a hole 535 onthe body surface 540. The hole 535 may be a natural hole on the bodysurface (e.g. mouth, meatus, nostrils, etc.) or an artificial hole (e.g.a hole formed in the skin by a surgical incision). After insertion, theproximal end of the device extends through the hole 535 and is exposedon the body surface. This is by way of example only, and the device mayin use be completely enclosed within the body. In this case, a surgicalcut is made in order to access the proximal end of the cover 510.

At any time after insertion, the outer cover 510 may be detached fromthe device 100 by deflating the balloons 515. This may be done, forexample, by inserting the syringe 530 into the valve 570 and drawing thefluid from the balloons so as to puncture the balloon by pulling on theplunger 550. Once the balloons have been deflated, the proximal end ofthe device 500 may be grasped and manually removed from the body leavingthe device 500 in place. If after removal of the outer cover 510, a newdetachable outer cover (not shown) becomes exposed on the shaft, thenewly exposed detachable layer may later on be removed from the device.

Sixth Embodiment

FIG. 7 shows an indwelling device 700 in accordance with anotherembodiment of the invention. The device 700 has a proximal end 702, adistal end 704, and a hollow cylindrical shaft 705. The shaft 705 has alumen 708. In this embodiment, the cover 710 lines the inner surface ofthe hollow shaft 705. The lumen 708 contains a cover 710 having thegeneral shape of a thin cylindrical shell covering the wall of the lumen708. The cover 710 is formed from a biocompatible, rigid material, suchas plastic. The proximal end of the cover 710 is glued to the lumen of arestraining ring 711. A circumferential clamp 750 around the ring 711secures the ring 711 to the proximal end 702 of the device 700.

FIG. 7 b shows the catheter of FIG. 7 a after insertion into the body.The catheter 700 was inserted into the body through a hole 735 on thebody surface 740. The hole 735 may be a natural hole on the body surface(e.g. mouth, meatus, nostrils, etc.) or an artificial hole (e.g. a holeformed in the skin by a surgical incision). After insertion, theproximal end of the device extends through the hole 735 and is exposedon the body surface. This is by way of example only, and the device mayin use be completely enclosed within the body. In this case, a surgicalcut is made in order to access the proximal end of the device 700.

FIG. 7 b further shows removal of the outer cover. The ring 711 isdetached from the proximal end 702 of the device 700, and the ring 711is removed from the device 700 together with the cover 710 attached toit. As the ring 711 continues to be pulled away from the proximal end702 of the device 700, the cover 710 becomes attenuated and detachesfrom the inner surface of the shaft lumen 708. If after removal of theouter cover 710, a new detachable outer cover (not shown) becomesexposed on the shaft, the newly exposed detachable layer may later on beremoved from the device.

Seventh Embodiment

FIG. 8 a shows an indwelling device 800 in accordance with a furtherembodiment of the invention. The device 800 has a proximal end 802, adistal end 804, and a cylindrical shaft 805 that may be solid or hollow.The shaft 805 is contained in an outer cover 810 having the generalshape of a thin cylindrical shell. The outer cover 810 is formed from abiocompatible, elastic material, such as latex, that was stretched overthe shaft 805, and allowed to contract on the shaft 805. The outer cover810 is reversibly attached to the shaft 805 by circumferential elasticforces in the outer cover 810 that are exerted on the shaft 805. Thisprevents slipping of the outer cover 810 over the shaft 805 duringinsertion of the device 800 into the body, and maintains the outer cover810 on the shaft 805 after insertion.

The outer cover 810 has a line of perforations 820 extending along thelength of the outer cover 810. A ring 811 located on the shaft 805contains a cord 830 that fixes the proximal end of the cover 810 ontothe shaft 805. As shown in FIG. 6, the device 800 may optionallycomprise a distally located annular clamp 615 that secures the distalend of the outer cover 810 to the shaft 805 and prevents debris fromaccumulating under the distal end of the outer cover 810 duringinsertion.

FIG. 8 b shows the device 800 after insertion into the body. The device800 was inserted into the body through a hole 835 on the body surface840. The hole 835 may be a natural hole on the body surface (e.g. mouth,meatus, nostrils, etc.) or an artificial hole (e.g. a hole formed in theskin by a surgical incision). After insertion, the proximal end of thedevice 800 extends through the hole 835 and is exposed on the bodysurface. This is by way of example only, and the device may in use becompletely enclosed within the body. In this case, a surgical cut ismade in order to access the proximal end of the cord 830. Relativemovement of the shaft 805 and the outer cover 810 is prevented duringinsertion due to the circumferential elastic forces of the outer cover810 on the shaft 805.

At any time after insertion, the outer cover 810 may be detached fromthe device 800. The cord 830 is released as shown in FIG. 8 c. Theproximal end of the perforation 820 is then torn. The cover 810 is thenmade to slide proximally over the shaft 805 as shown in FIG. 8 d. Thiscauses a new region of the perforation 820 to be exposed outside thebody. This section of the perforation is then torn, and the cover 810 isthen made to slide proximally over the shaft 805 (FIG. 8 d). Thisprocess continues until all of the perforation 820 is completely tornand the cover is removed from the body. If after the removal of theouter cover 810, a new detachable outer cover (not shown) becomesexposed on the shaft, the newly exposed detachable layer may later on beremoved from the device.

Eighth Embodiment

FIG. 11 a depicts a further embodiment of the device of the presentinvention, comprising an elongate catheter 1100 bearing an outer cover1110 on its external surface. The cover 1110 is situated in closeapposition to the outer surface of catheter 1100 along almost the entirelength thereof. In some versions of this embodiment, the cover mayextend over the entire length of the device. In addition, two sealingelements—a distal sealing tip 1120 and a proximal sealing element1130—ensure that cover 1110 and the outer surface of catheter 1100 arein very close contact at their distal and proximal ends respectively,thus preventing the passage of possibly contaminating fluids (e.g.blood, urine, tissue fluid) between said catheter and said outer cover.In the typical device according to this embodiment shown in FIG. 11 a,the distal sealing tip 1120 is elongate in shape, while the proximalsealing element 1130 is depicted as an annular ring. FIG. 11 b depictsan alternative version of elongated distal sealing tip 1120. Thefunction of the perforations 1140 present in the distal half of thisversion of the sealing element is to provide a fluid pathway for use incases in which it is desired that substances such as pharmaceuticalagents and the like will be released from the indwelling device into theblood stream, duct or tissues. In yet other alternative forms of thedistal sealing tip 1120, the internal side of the distal half of thesealing tip, in which are present one or more apertures or perforations,may be covered with a mesh, thereby providing mechanical support andstrength without interfering with the desired fluid flow channelprovided by said apertures. It is to be further noted that it ispossible to use many other shapes and forms of sealing elements, all ofwhich are included in the scope of the present invention.

According to one preferred embodiment of the invention, a thin layer ofmineral oil or similar biocompatible fluid is present between eachadjacent pair of covers (in the case that the device is fitted with asequential stack of covers, as described hereinabove) and/or between theinnermost cover and the indwelling medical device itself. The presenceof the inter-layer oil is advantageous both in providing an extramechanism for preventing the ingress of contaminating fluids, as well asacting as a lubricant in order to facilitate the removal of the layer(s)from each other and/or from the surface of the medical device. In thecase that mineral oil is incorporated into the device as describedherein, the sealing elements may usefully be constructed of anoil-absorbing material.

In one particularly preferred embodiment of this type of device, boththe outer cover 1110 and the distal sealing tip 1120 are made of medicalgrade polyurethane. In such a case, however, the polyurethane used toconstruct the cover 1110 will usually be of a harder grade (i.e. have ahigher Shore rating) than that used to manufacture the sealing tip 1120.However, other biocompatible materials such as silicones, PVC, mylar andnylon may also be used to manufacture the outer cover 1110 and distalsealing tip 1120.

The proximal sealing element 1130 is most conveniently manufactured frompolyurethane, but any other suitable material such as silicones, PVC,mylar and nylon may also be employed, and as such fall within the scopeof the present invention as claimed.

The abovementioned materials that may be used to construct the medicaldevice (e.g. catheter), outer cover and proximal and distal sealingelements may be used in any of the available degrees of hardness andcolor (including colorless transparent). In addition, any of thesematerials may be prepared such that they incorporate radio-opaquesubstances, for use as markers, as is known in the art. The embodimentof the device shown in FIG. 11 a also incorporates a stationary cuttingblade 1150 in its proximal, preferably extra-corporeal, portion. Asshown in FIG. 11 a, the proximal sealing element 1130 may be situatedexternal to (and separate from) the blade. Alternatively, said elementmay be mounted close to the blade, within the blade housing itself (notshown).

Blade 1150 is used to assist in the removal of the outer cover 1110(together with its attached biofilm deposits) in the following manner.Firstly, in the event that proximal sealing element 1130 is situatedexternal to blade 1150 (as indicated in FIG. 11 a), said element isopened and removed from the device and (if necessary) from the body. Inthe event that the proximal sealing element exists as an integral partof the blade housing, this stage is not required. In a further versionof this embodiment of the invention, the proximal sealing element isconstructed such that it may adopt two different conformations. In thefirst of these conformations, the sealing element is capable ofpreventing ingress of fluids into the space between the proximal end ofthe covers(s) and the medical device. In the second of theseconformations, the proximal sealing element adopts a position such thatthe tight seal between the cover and underlying medical device is lostin the region of said element, thereby facilitating the removal of thecover layer and any biofilm attached thereto. Consequently, when thedevice is constructed in this manner, the first stage of the coverremoval process consists of changing the conformation of the proximalsealing element from the first conformation to the second conformation.

The proximal margins of the outer cover 1110 are then grasped betweenthe operator's fingers and drawn in a proximal direction toward theblade 1150. Upon making contact with the blade, outer cover 1110 isincised at its free edge. This initial incision becomes elongated as theproximal margins of cover 1110 are drawn still further in a proximaldirection, until the entire length of said cover has been cutlongitudinally, and removed from contact with the catheter 1100 andfinally entirely withdrawn from the body.

FIG. 11 c illustrates the shape and form of cutting blade assembly 1150in greater detail. The distal, ramp-like portion 1160 of the bladepossesses a rounded, non-sharp profile which leads into the cutting edge1170 of the blade assembly. It will thus be appreciated that when, asdescribed hereinabove, the outer cover 1110 is drawn in a proximaldirection towards cutting blade assembly 1150, the distal, ramp-likeportion 1160 will serve to guide the free proximal margin of said covertowards cutting edge 1170. This guiding mechanism serves to prevent thekinking or buckling of cover 1110 that might otherwise occur if theproximal margin of said cover were to encounter a sharp, angled blade.

The cutting blade 1150 may be constructed from any suitable materialthat will permit said assembly to function as described hereinabove. Ina preferred embodiment, however, the material used to construct thecutting blade 1150 is constructed from a sharpened metal such as medicalgrade stainless steel. In other embodiments, the blade may beconstructed from other suitable biocompatible metals, as well as fromrigid plastic materials.

The cutting blade assembly 1150 may be mounted in a stationary positionat any convenient point at the proximal end of the device. In aparticularly preferred embodiment, as shown in the exploded view givenin FIG. 11 d, cutting blade assembly 1150 is located within a multipleluer lock fitting 1180, of any of the types that are well known in theart.

It is to be emphasized that the various components described in thisembodiment of the device of the invention (i.e. the distal and proximalsealing elements and the stationary cutting blade) may all beincorporated into a single device, as illustrated in FIG. 11 a.Alternatively, a single device may incorporate only one or two of thethree elements disclosed hereinabove. It should further be noted thatthe presently-described embodiment is suitable for use both inconjunction with a single cover and with a stack of covers, as is thecase with the other embodiments disclosed and described hereinabove.

While specific embodiments of the invention have been described for thepurpose of illustration, it will be understood that the invention may becarried out in practice by skilled persons with many modifications,variations and adaptations, without departing from its spirit orexceeding the scope of the claims.

1. A medical device for insertion into a body, the device having atleast one surface covered by and attached to at least one detachablecover, the cover being detachable from the surface and removed from thebody any time after the device has been inserted in the body, whereinthe presence of said cover does not prevent the device from fulfillingits intended function, and wherein said medical device is selected fromthe group consisting of: (a) a catheter; (b) a cannula; (c) a drain; (d)a stent; (e) a pacemaker; and (f) an electrode.
 2. The device accordingto claim 1, wherein said device is a urinary catheter.
 3. The deviceaccording to claim 1, wherein said device is a venous catheter.
 4. Thedevice according to claim 1, wherein said device is a dialysis catheter.5. The device according to claim 1, having a stack of at least twosequentially detachable covers, each cover being detachable either fromthe surface of the device or from the adjacent cover, and removed fromthe body while the device is within the body.
 6. The device according toclaim 5, wherein the at least two covers are identical.
 7. The deviceaccording to claim 1, wherein the cover is formed from a materialselected from the group consisting of: (a) rubber; (b) silicone rubber;(c) polyvinylchloride; (d) latex; (e) woven metal mesh; (f) parylene;(g) polyurethane; (h) mylar; and (i) nylon.
 8. The device according toclaim 1, wherein the cover is formed from a biocompatible material. 9.The device according to claim 1, wherein the cover is formed from anon-allergenic material.
 10. The device according to claim 1, whereinthe cover has a smooth surface.
 11. The device according to claim 1,wherein the cover has a rough surface.
 12. The device according to claim5, containing a pharmaceutical agent between two adjacent covers. 13.The device according to claim 12, wherein the pharmaceutical agent is ananti-infective agent.
 14. The device according to claim 13, wherein theanti-infective agent is an antibiotic drug.
 15. The device according toclaim 1, wherein the cover is reversibly attached to a surface byelastic forces in the cover.
 16. The device according to claim 1,wherein the cover is detachable from the surface by tearing the cover.17. The device according to claim 1, wherein the cover is tearable alongone or more preformed seams or perforations in the cover.
 18. The deviceaccording to claim 1, comprising a blade slidable over the surface so asto cut the cover and detach the cover from the surface.
 19. The deviceaccording to claim 1, further comprising a ring placed at a distal endof the shaft to prevent materials from entering between the cover andthe surface.
 20. The device according to claim 1, wherein the covercomprises an inner cylindrical shell and an outer cylindrical shell, theinner and outer cylindrical shells each having a distal end and aproximal end, the inner and outer cylindrical shells being attached toeach other at their proximal ends and at their distal ends.
 21. Thedevice according to claim 1, comprising one or more balloons locatedbetween the cover and the surface, the cover being attached to thesurface when the balloons are inflated, and detached from the surfacewhen the balloons are not inflated.
 22. The device according to claim 1,wherein the cover is impenetrable to microorganisms.
 23. The deviceaccording to claim 1, wherein the cover is impenetrable to water. 24.The device according to claim 1 any one of the precious claims, whereinthe cover stores and releases a substance.
 25. The device according toclaim 24, wherein the substance is an anti-microbial or anti-fungalcompound.
 26. The device according to claim 1, wherein the cover has twoparallel rows of perforations or seams separating a strip of the cover,the strip being attached at a distal end to a first end of a cord and asecond end of the cord being accessible at a proximal end of the device.27. The device according to claim 1, further comprising a cutterslidable along the surface of the device, the cutter being configured tocut the cover when sliding along the surface.
 28. The device accordingto claim 1, wherein the cover has a row of perforations such that whenthe proximal end of the perforation is torn, the cover may be made toslide over the surface in a proximal direction.
 29. The device accordingto claim 1, further comprising a distal sealing tip, wherein said tip iscapable of preventing ingress of fluids into the space between thedistal end of the cover(s) and the medical device
 30. The deviceaccording to claim 29, wherein the distal sealing tip is made ofpolyurethane.
 31. The device according to claim 1, further comprising aproximal sealing element, wherein said element is capable of preventingingress of fluids into the space between the proximal end of thecovers(s) and the medical device.
 32. The device according to claim 1,further comprising a proximal sealing element, wherein said element isconstructed such that it may adopt two distinct conformations, such thatwhen the sealing element is in the first conformation, said element iscapable of preventing ingress of fluids into the space between theproximal end of the covers(s) and the medical device, and when thesealing element is in the second position, said element permits easyremoval of the outer cover, together with the associated biofilm. 33.The device according to claim 31 or claim 32, wherein the proximalsealing element is made of polyurethane.
 34. The device according toclaim 1, further comprising a fixed blade attached to the proximal endof said device, such that said blade is capable of incising the cover,when said cover is pulled proximally toward said blade.
 35. The deviceaccording to claim 1, further comprising a distal sealing element asdefined in claim 29, a proximal sealing element as defined in claim 31or claim 32 and a fixed blade as defined in claim
 34. 36. A method forpreventing biofilm buildup on the surface of an indwelling medicaldevice that has been inserted into the body of a subject, said methodcomprising the steps of: a) providing a medical device fitted with adetachable cover attached to at least a portion of its outer surface,such that the presence of said cover does not interfere with theintended function of said device; b) inserting said device together withits attached cover into the body of the subject; c) detaching the coverfrom the outer surface of the medical device and removing said coverfrom the body together with any biofilm deposited on the surface of saidcover, while leaving the device inside the body such that it maycontinue to fulfill its intended function.
 37. A method for preventingbiofilm buildup on the surface of an indwelling medical device that hasbeen inserted into the body of a subject, said method comprising thesteps of: a) providing a medical device fitted with a stack of two ormore sequentially detachable covers, such that the innermost cover isattached to at least a portion of its outer surface, and wherein thepresence of said stack of covers does not interfere with the intendedfunction of said device; b) inserting said device together with itsattached cover into the body of the subject; c) detaching the outermostcover from the stack of sequentially detachable covers and removing saidcover from the body together with any biofilm deposited on the outersurface thereof, while leaving the device inside the body such that itmay continue to fulfill its intended function; d) subsequently repeatingstep (c) for the one or more remaining outermost covers.
 38. The methodaccording to claim 36 or claim 37, wherein the medical device isselected from the group consisting of: (a) a catheter; (b) a cannula;(c) a drain; (d) a stent; (e) a pacemaker; and (f) an electrode.
 39. Themethod according to claim 38, wherein the device is a urinary catheter.40. The method according to claim 38, wherein the device is a venouscatheter.
 41. The method according to claim 38, wherein the device is adialysis catheter.